Fire-control apparatus.



A. BARR & w. STROUD.

FIRE CONTROL APPARATUS.

APPLICATION FILED DEC-30, 1911.

1,177,470. Patented Mar. 28, 1916.

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A. BARR & W. STBOUD. FIRE CONTROL APPARATUS. APPLICATION men 050.30.19H.

1,177,470. Patented Mar. 28, 1916.

5 SHEETS-SHEET 2- A. BARR & W. STROUD.

FIRE CONTROL APPARATUS. APPLICATION FILED DEC. 30, I911.

1,177,470. Patented Mar. 28, 1916.

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Patented Mar. 28, 1916.

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A. BARR & W. STROUD.

' FIRE CONTROL APPARATUS.

APPLICATION FILED DEC. 30. I911.

1,177,470. F/G Patented Mar. 28, 1916.

si 6' 5 SHEET$SHEET 5- I 63 72 77 7/ W 75 65 gnaw-w??? 3' f5 S w 5/ 6'5A J8 9/ /!4 is a 88 62 I MMI1MPEI g2 x89 64 ARCHIBALD BARR AND WILLIAMSTROU'D, OF ANNIESLAND, GLASGOW. SCOTLAND.

FIRE-CONTROL APPARATUS.

Specification of Letters Patent.

Application filed December 30, 1911. Serial No. 668,799.

To all whom it may concern Be it known that we, ARGHIBALD Bean andWILLIAM STRoUD, subjects of the Klng of Great Britain and Ireland, andboth of. 'Caxton street, Anniesland, Glasgow, -Scotland, have invented anew and useful Fire- Control Apparatus, an instrument for indicatingrange and rate of change of range and for finding the rate of transversemotion of the target, (for which we have made an application for patentin Great Britain,

I No. 1,510, bearing date January 20, 1911,)

of which the following is a specificatlon.

The object of our invention is to provide an instrument capable ofreadily indicatlng the rate of change of range and the rate oftransverse motion of the target when the direction and velocity of ourown ship hereinafter generally referred to as the observing ship areknown, and the direction and velocity of the target are either known orare capable of estimation, and further, assuming the range known at anytime, to provide means for indicating the value of the actual range ofthe target at later times.

We are aware that apparatus has already been devised for attaining thesame general results as those which we accomplish by our invention,but'this has been done by apparatus differing in principle ofconstruction and method of operation from that which forms the subjectof our invention.

In addition to securing the results attained by apparatus such as hasalready been devised, our present invention possesses the advantage thatthe act of sighting upon the target mechanically determines the rate oftransverse motion of the target and the rate of change of range at once.Further, the mechanism may be so arranged that the results of theobservations may be automatically transmitted to a distance, and lastlythe mechanism for measuring the magnitude of the rate of change of rangemay be associated in construction with means for automaticallyfurnishing the value .of thetotal change of range, or if the initialrange be known, the actual ranges at later times.

This invention will be described with reference to the accompanyingdrawings,- in which Figure 1 is a diagram representing the velocities ofthe observing ship and that of the target and the components of therelative velocities it is desired to indlcate and Patented Mar. 28,1916.

transmit to a distance. Fig. 2 is a plan of the interior parts of oneform of an instrument constructed in accordance with our invention. Theposition in which the parts are shown corresponds to that of the lines1n the velocity diagram Fig. 1, but the casing in which the mechanism iscarried is omitted to gave a clearer view of said mechanism. Fig. 3 isanelevation partly in section taken about the line X -X of Fig. 2,looking in the direction of the arrow. Fig. 3 is an elevation partly insection taken about the line AB of Fig. 2, looking from the right towardthe left. plan of a modified form of instrument, the casing being shownin section and the section being taken below a sight bar hereinaftermentioned. Fig. 5 is the velocity diagram corresponding to the modifiedform of apparatus, shown in Figs. 6, 7 and 8. Fig. 6 is a plan of theoutside seen from above, Fig. 7 is a sectional elevation approximatelyabout the line G G of Fig. 8, and Fig. 8 isa plan of-the lower part ofthe mechanism the case being sectioned at about the level F F of Fig. 7

An explanation of the known principle upon which this invention is basedwill now be given with reference to the diagram shown at Fig. l of thedrawings, in which B represents a vertical axis fixed relatively to theobserving ship on which the instrument is mounted, BA represents a lineof sight to be turned about the axis B as center. 0 represents a pointcapable of being adjusted along a line intersecting the axis B andparallel to the direction of travel of the observing ship, so that thedistance CB may be set to represent the velocity of the observing shipin magnitude and the line CB represent the direction of travel of. theobserving ship. D represents a point capable of'being turned about C asa center and adjusted so that the line CD may be set parallel to thedirection of'motion of the target and the distance CD set to representthe velocity of the target. The speedof the target and its direction oftravel'may be determined or estimated in any way. In use, with thepoints C and D, set and fixed relatively to the observing ship, assumingthat .the target and the observing ship each maintains its speed anddirection, if the line of sight BA, which always passes through the axisB is kept directed upon the target, the

rate of change of range is determined by the resolved component BH ofthe line BD along the line of sight BA, and the rate of transversemotion of the target, which is perpendicular to the line of sight BA, isdetermined by the resolved component DH of the line BD perpendicular tothe line of sight. The speed of the observing ship, as set off by thedistance of C- from B, and the speed of the target, as set off by thedistance of D from C, and the direction of motion of the target, asindicated by the position of D relatively to C, are adjusted from timeto time as changes in these are observed. It will thus be recognizedthat for practical purposes the values of the components BH and DH arecapable of being readily and accurately determined. type already knownthis has been done by means of ocular observations taken on the lines BAand DH. Thus given the velocity and direction of the observing ship andthat of the target, we have two points B and D upon asurfaceapproximately horizontal, and the primary object of this invention is tomechanically ,determine the projections BH, DH of the line BD along andperpendicular to the'line of sight through B.

In the examples of construction illustrated, the operation of keepingthe line of sight BA directed 'upon the target, brings the mechanismprovided into action and causes rotary motions to be imparted to shafts,the amounts of rotation of which indicate, one the rate of change ofrange and the other the rate of transverse motion of the target. Therotation of these shafts may be used to operate indicators for givingthe values of,BH

and DH; they may be used to operate mechanism for automaticallytransmitting to a distance the'values of the resolved components BH andDH, or either of them; a shaft rotated in accordance with change ofrange BH may be associated in construction with means for automaticallyfurnishing the value, of the total change of range, or if the initialrange be known, the actual range at later times.

In Fig. 2. (for which, as-stated,Fig. 1 is the velocity diagram) theinstrument is placed with-the line BC in the fore and aft direction ofthe observing ship and the position of the point C is adjusted-withreference to B so that CB indicates the speed of the observing ship.This is accomplished v by turning the head 1 which rotates a screw 2carrying a nut 3 upon which is mounted a pivot C, the vertical axis ofwhich will also be designated C and in further reference implied exceptwhere otherwise qualified. The length of CB (and, therefore, the speedof the observing ship) is indicated by the position of the fixed pointer4 upon the dial 5 attached to the worm wheel 6 which is open ated by thehead 1 through the worm 7 The direction of motion of the target (CD Inapparatus of the- Fig. 1) is set off in the following way :-8 1s aslotted bar pivoted at C carrying a slider 9 from which the pin Dprojects upward.

the base of the instrument which a am is fixed relatively to theobserving ship, but on releasing both these clamps the pinD may be movedto or from C or around C by manipulating the heads 12 and 13. The head12 is mounted on the rod Q on which is feathered a pinion wheel Pgearing in the rack R ivoted on the pin D, the connection permltting therack R? to turn freely about the pin D. Similarly, the head 13 is fixedto a rod Q upon which is feathered a bevel wheel 14 gearing into a bevelwheel 15 to which is fixed the pinion wheel P gearing in the rack B Thisrack R is incapable of translation. The two racks R and R are keptalways perpendicular to each other by being mounted in a piececontainingtwo slides S S at right angles to each other. Thus, when the pin D isfree, the head 12 and the pinion P may be rotated whereby the rack R ismoved endwise carrying thepin D in the fore and aft direction. Byrotating the head 13 the pinion wheel P is rotated upon the rack R whichis incapable of translation so that P moves forward or backward upon Rcarrying the rack R and pin D with it. Thus by manipulating the heads 12and 13 the pin D may be' placed in any position with reference to Cuntil the line CD represents the speed of the target as read off on thescale 16 and the direction as set off upon the scale 17. The pin D isnow clamped in position by means of 10 and 11 and the axes B, C and Dthen remain fixed relatively to the observing ship, after which thesight-bar EF .parallel to BA is turned around so as to look in thedirection of the target, so that when properly directed the position ofthe point H on the line BA is automatically determined and anysubsequent variation in the direction of the line of sight isaccompanied by a variation of the component BH and necessitates acorresponding travel of P along its rack R and any variation of DHnecessitates a corresponding travel of the pinion P along its rack-Reach of the pinions producing a rotation of its associated shaft Q or Qeach of which consequently indicates the .magnitude of the respectivealterations 0ccurring. -The sight-bar EF (of which E is the back-sightand F the fore-sight) is mounted upon a frame G (which also carries theguides S S, the rods .QE'Q and associated parts) all of which arecapable of being rotated together about the vertical axis B when the pinD is fixed. As seen at Fig. 3 the frame G, is mounted to turn about apivot G the. axis of which is the vertlcal axis B. The frame G with thesight bar and other parts may either be turned by hand directly or moreslowly by the manipulation of 12 and 13. The resolved components BH andDH of the velocity CD parallel to, and at right angles to the line ofsight are now represented by the position of P upon the rack R and bythe position of P upon the rack B respectively. We next provide meansfor indicating the positions of these pinion wheels upon theirrespective racks. The position of P is indicated by the revolutions ofthe rod Q to which is attached a pinion 18 gearing into a wheel 19 witha uniform scale upon its face. The fixed pointer 20 enables the rate ofchange of range or value of the component BHto be read off. Similarlythe position of P is indicated by the revolutions of the rod Q to whichis attached a pinion 21 gearing into a wheel 22 with a uniform scaleupon its face. The fixed pointer 23 enables the differential velocity ofthe observing ship and the target at rightangles to the line of sight orvalue of the component DH to be read ofi.

Fig. 4 shows in plan a modified arrangement (for which Fig. 1 is againthe velocity diagram) according to this invention and in addition to theindicators shown in Fig. 2 there is represented means for integratingthe product of the rate of change of range and time. BA as beforerepresents the line of sight or, in other words, the sight bar isparallel to BA. In this case the equivalent of a sight-bar isconveniently formed by providing a fore-sight and a back sight similarto E and F of Fig. 2, on the upper part of the case which is cut away inthis view. The pin D corresponds to the similar pin in Fig. 2 and itsposition may be adjusted by means similar to'those described inconnection with Fig. 2. Thus the parts 1 to 11, 16, 17 and pin Ovshownon Fig. 2 may be used in this modification for the purposes described.The resolved components BH and DH of BD'along and perpendicular to theline of sight are here measured directly by screw mechanism which alsowork transmitters whereby the results may be telegraphed to recelvers ata distant station. Surrounding the pm D are two slotted pieces 24 and25, the distance of 24 from B measuring the rate of change of rangerepresented by the component BH and the distance of 25 from B' rate oftransverse motion of the target represented by the component DH. In thefirst instance we shall consider the measurement of the rate of changeof range. The slotted piece 24 is carried upon a nut 26 which istranslated by the screw 27 operated by the head 28. In order to guidethe slotted piece 24 steadily, the rotations of the screw 27 aretransmitted to the screw 29 by two sets of bevel gearings 30, 31 and 32,33 operating through a shaft 34 supporting the commutator 35 of atransmitting apparatus. Upon the screw 29 is a nut 36 attached to theleft hand end of the slotted piece 24. Forked into the piece 24 is afriction wheel 37 mounted on a shaft 38 upon which it is feathered. Auniformly rotating friction disk 39 driven for example by clockworkcontained in the case, 93, and wound up by the head, 94 presses againstthe friction wheel 37 thereby causing it to rotate at a rate dependingupon the distance of 37 from the center of the friction disk 39. Theposition of this center is such that when the friction disk is there EDis perpendicular to the line of sight BA. Through bevel' gearing 40, 41the revolutions of the shaft 38 are transmitted to the carry over drums42, 43, 44, indicating ranges. These drums besides being driven by thefriction gear, 37, 39 may be so arranged as to be also readily rotatableby hand in such a way that the initial range (as given by therangefinder e. 9.) may be immediately set upon the drums, when, if thepin D has been correctly placed and'the line of sight has been keptcontinuously upon the target, the range as given by the reading of thedrums should keep in conformity with themeasured range. The carry-overmechanism between the drums, 42 and 43, and the drums 43 and 44 is notshown. The arrangementmay be similar to that commonly used in countingtaching to the shaft 27 a worm 45 gearing into a worm wheel 46 uponwhich a circular scale, with a fixed pointer, is mounted.

The arrangements for measuring, indicating and transmittingv the rate oftransverse motion of the target are precisely similar to those describedin connection with rate of change of range. The slotted piece 25,

say below the piece 24 is attached to a nut 47 operated by a screw 48 bymeans of the head 49 through bevel gearing 50, 51,'shaft 52 (carryingcommutator 53) and bevel gearings 54, 55. In order to guide the slottedpiece, 25, steadily a drive is applied toits end opposite to 47 andsimilar tc'that applied thereto, by'means of a screwed extension, 48, ofthe shaft to which the head,

v49, is fixed. The rate of transverse motion of the target may be readoff by worm 56 (attached to screw 48.) and worm wheel 57 carrying acircular scale just as described in connection with 45' and 46. It willbe recognized that the screws, 27, 29 and 48, 48 may be of appropriatelyquick pitch to permit rotational motion to be imparted to them when thesight bar is turned by the forces transmitted from the slotted pieces,24 and 25 bearing against the fixed pin, D. The transmitters andreceivers referred to may conveniently be of the type described in theapplicants earlier Patent No. 1009013, but transmitters and receivers ofother types may be used in connection with the apparatus. Thecommutators and 53 may be of any appropriate rotary type, for examplethey may be of the rotary cylindrical kind as disclosed with referencetoFigs. 9 to 12 of applicants aforesaid" Patent No. 1,009,013.

In the modified form of apparatus shown in Figs. 6, 7 and 8 (for whichas stated, Fig. 5 is the velocity diagram) 60, 61 is the sight'barparallel to BA, Fig. 5 and coincident with BA Fig. 6. This sight bar ismounted upon the drum portion of a casing 62, and can be rotated by thehandle 63 about the vertical axis B, so as to be kept continuouslydirected uponthe target. At-

- tached to this casing 62 are the bearings of (say) three sets ofshafts 64, carrying equal pinions 65 fixed to the shafts. These pinionsgear into large toothed wheels 66 and 67 (see Figs. 7 and8). The wheel67 is fixed to the stand of the apparatus so that in this way the wheel66 is maintained in such a way that it does not rotate with the casing62. Thus this wheel 66 and all parts that it supports, after the initialsettings of the parts have been made, remain fixed relatively to theobserving ship, and do not rotate when the sight bar is turned about thevertical axis B. To set off the velocity of the ob-'' serving ship ahandle 69 is turned which causes an index dial 71 and a screw 78 to berotated. As shown at Fig. 7, the screw in rotating moves a frame 72 inthe fore and aft direction and C (which is represented by the axis of ashaft,.having a handle 73,

mounted to rotate in a bearing upon the frame 72) can thus be set at therequired distance from the vertical axis B, the pointer indicating uponthe dial 71 the velocity BC required (say 20.4). To set off the speed ofthe .target the handle 73 isturned which causes a screw 79 and an indexdial 76, both mounted upon a frame 7 7, to be rotated. As

shown at Fig. '7, a pin 80- (the center of' which represents thevertical axis 1)) is attached to a nut '81 which is mounted upon thescrew 79 so that as the screw 79 is rotated the pin 80 or axis D ismoved toward or away from C and the speed DC (say 16.5) is indicatedupon the dial by the pointer 74, see Fig. 6. In Fig. 7 the parts 73 and76 are represented for clearness as standing at some height above'theapparatus. In the actual apparatus as constructed, the plate 76 wouldlie close above 77. To set ofi the direction of motion of the target ahandle is turned which causes the frame 77, the screw 79, pin D andpointer 74 to turn about C, so that the line joining C and the pointer74, or in other words, the line CD, can thereby be set parallel to thedirection of motion of the target. We have in the next place to indicateand record the projection of the line BD, Fig. 5 along and perpendicularto the line of sight. This will be understood from Fig. 8. The pin isembraced by a square or rectangular piece 121 which engages in twoslotted bars 82 and 141. The slotted bar 82 (see Fig. 7) carries tworacks 83, 84, engaging with pinions 85 and 86 fixed on a shaft 87,carrying a toothed wheel 88 gearing into a pinion 89 to which thecommutator 90 of a transmitting apparatus is attached when it is desiredto transmit the indications to a distance. If, however, it were desiredto indicate at the instrument itself the shaft 87 'might have beenprolonged outside the casing 62, and a counting or indicating mechanismattached to it. In a similar manner the slotted bar 141 communicates itsmotion by means of racks and pinions to the shaft 91 whichv can bearranged to indicate the rate of transverse motion of the target eitherat the instrument by means of an indicating mechanism, or counter, or ata distance by means of a commutator 92 of a transmitting apparatus. Tocomprehend the method of working it must be understood that the pin 80is fixed (after setting) and as the drum casing 62 is rotated soas tokeep the line of sight 60, 61 upon the target the slotted bars 82 and141 bear against. the pin 80 and are thereby caused to move and producea rotation of the shafts 87 and- 91, whose motions indicate the rate ofchange of range and the rate of transverse motion of the targetrespectively.

The stationary portion of the frame 67 (Fig. 7) is shown carrying eightinsulating rings, two of these are connected to the and terminalsof asupply of E. M. F., the remaining six are in two sets of three for usein connection with the two commutators 90 and 92.

On the left of Figs. 7 and 8 is shown a constant speed motor 93 suppliedwith current from the and rings on the frame 67, driving a friction disk39, say, by means of a worm and worm wheel. The description of thecorresponding parts in Fig. 4 applies to the case of Figs. 7 and 8.

In the claims the rack R of Fig. 2, the frame 25 of Fig. 4 and the frame141 of Fig.

substituted therefor will generally be termed the transverse bar, andfor purposes of definition it may be assumed that the bars are withoutbreadth.

1. Apparatus for use in fire control having a fixed base, a verticalaxis B fixed relaangles to the line of sight, the longitudinal tively tothe base, a sight bar mounted on the base capable of rotation about thecenter B, a part mounted upon the base about a vertical axis C and sosupported that the distance CB may be adjusted to represent on a chosenscale the speed and direction of motion of the home ship, a part mountedupon the base about a vertical axis D adjustable relatively to C, sothat CD may be set to represent on the chosen scale the speed anddirection of motion of the target, a longitudinal bar maintainedparallel to the line of sight, a transverse bar maintained at right andtransverse bars being mounted to turn with the sight bar, means forcausing the transverse bar to intersect the axis D at all times, andmeans for indicating the distance between D and the point where the lineof sight through B intersects the transverse bar, together with meansfor indicating the distance between the vertical'axis B and thetransverse bar, for the purposes set forth.

2. Apparatus for use in fire control having a fixed base, a sight barmounted on the base capable of rotation about a vertical axis B fixedrelatively to the base, a part mounted upon the base about a verticalaxis C and so supported that the distance CB may be adjusted torepresent on a chosen scale the speed and direction of motion of theobserving ship, a part mounted upon the base about a vertical axis Dadjustable relatively to C, so that CD may be set to represent on thechosen scale the speed and direction of motion of the target, alongitudinal barmaintained parallel to the line of sight, a trans versebar maintained at right angles to the line of sight, the longitudinaland transverse bars being so mounted as, at all times,

to intersect in the axis D and each capable of moving in a directionperpendicular toits length toward or away from the axis B,

and turning with the sight bar, with means for indicating the distancesof the longitudinal bar and the transverse bar from the base about avertical axis C and so supported that the distance CB may be adjusted torepresent on a chosen scale the speed and direction of motion of theobserving ship, a part mounted upon the base about a vertical axls Dadjustable relatively to C, so that CD may be set to represent on thechosen scale the speed and direction of motion of the target, alongitudinal bar maintained parallel to the line of sight, a transversebar maintained at right angles to the line of sight, the longitudinaland transverse bars being mounted to turn with the sight bar, means forcausing the transverse bar to intersect the axis D at all times, andmeans for indicating the distance between D and the point where the lineof sight intersects the transverse bar, together with means forindicating the distance between the vertical axis B and the transversebar, a friction disk, means for uniformly rotating the friction disk, a

adjusted to represent on a chosen scale the v speed and direction ofmotion of theobserving ship, a part mounted upon the base about avertical axis D adjustable relatively to C, so that CD may be .set torepresent. on the chosen scale the speed and direction of motion ofthetarget, a longitudinal bar maintained parallel to the line of sight, atransverse bar maintained at right anglesto the line of sight, thelongitudinal and transverse bars being so mounted as, at all times, tointersect in the axis D and. each capable of moving in a directionperpendicular to its length toward or away from the vertical axis B andturning with the sight bar, a

the friction disk, a'friction wheel carried by the transverse bar andarranged to move disk, for the purposes set forth. 5. Apparatus for usein fire control having a fixed base, a sight bar mounted on the basecapable of rotation about a vertical axis B fixed relatively to thebase,a part mounted upon the base about a vertical axis C and sosupported that the distance ,CB may be adjusted to represent on a chosenscale the speed and direction of motion of the observing ship, a partmounted upon the base about a vertlcal axis D adjustable relatively toC, so that CD may be set to represent on the chosen scale the speed anddirection of motion of the target, a longitudinal bar maintainedparallel to the line of sight, a transverse bar maintained at rightangles to the diameter of the face of the friction disk, for

disk, a friction wheel carried by the transverse bar and arranged tomove along a the purposes set forth 6. Apparatus for use in fire controlhaving a fixed base, a sight bar mounted on the base capable of'rotation about a vertical axis B fixed relatively to the base, a partmounted upon the base about a vertical axis 0 and so supported that thedistance CB may be adjusted to represent on a chosen scale the speed anddirection of motion of the observing ship, a part mounted upon the baseabout a vertical axis D adjustable relatively to C, so that CD may beset to represent on the chosen scalethe speed and direction of motion ofthe target, a longitudinal bar maintained parallelto the line of sight,a transverse bar maintained at right angles to the line of sight,thelongitudinal and transverse bars being mounted to turn with the sightbar, means for causing the transverse bar to intersect theaxis D at alltimes, a shaft and means for rotating it in conformity with thevariations in the distance between D and where the line of sightintersects the transverse bar, together with a second shaft and meansfor rotating it in conformity with the variations in the distancebetween the vertical axis B and the transverse bar, for the purposes setforth. I

7 .'Apparatus for use in fire control having a fixed base, a sight barmounted on the tively to C, so that CD may be set to repre sent on thechosen scale the speed and direction of motion of the target, alongitudinal bar maintained parallel to the line of sight, a transversebar maintained at right angles to the line of sight, the longitudinaland transverse bars being so mounted as, at all times, to intersect inthe axis D and each capable of movlng in a dlrection perpendicular toits length toward or away from the vertical axis B and turning with thesight bar, a shaft and means for rotating it in conformity with thevariations in the dis- 7 tance between the longitudinal bar and the axisB, and a second shaft and means for rotating it in conformity with thevariations in the distance between the transverse bar and the center B,for the purposes set forth.

8. Apparatus for use in fire control having a fixed base, a sight barmounted on the base capable of rotation about a vertical axis B fixedrelatively to the base, a part mounted upon the base about a verticalaxis C and so supported that the distance CB may be adjusted torepresent on a chosen scale the speed and direction of motion of theobserving ship, a part mounted" upon the base about a vertical axis Dadjustable relatively to C, so that-CD may be set to represent on thechosen scale the speed and direction of motion of the target, alongitudinal .bar maintained parallel tb, the line of sight, atransverse bar maintained at right angles to the line of sight, thelongitudinal and transverse bars being so mounted as, at all times, tointersect in the axis D and each capable of moving in a directionperpendicular to its length toward or away from the vertical axis B andturning withthe sight bar, a shaft and means forrotating it inconformity with the variations in the distance between the longitudinalbar and the center the, commutator of a transmitter mounted on ordrivenby the said shaft, for the purposes setforth.

. 9. Apparatus for use in fire control having a fixed base, a sight barmounted on the base capable of rotation about a vertical axis B fixedrelatively to the base, a part mounted upon the base about a verticalaxis C and so supported that the distance CB may be adjusted torepresent on a chosen scale the speed and direction of motion of theobserving ship, a part mounted upon the base about a vertical axis Dadjustable relatively to C, so that CD may be set to represent on thechosen scale the speed and direction of motion of the target, alongitudinal bar maintained parallel to the line of sight, a.

transverse bar maintained at right angles to the line of sight, thelongitudinal and transverse bars being so mounted as, at all times, tointersect in the axis D and each capable of moving in a directionperpendicular to its length toward or away from the vertical axis B andturning with the sight bar, a shaft and means for rotating it inconformity with the variations in the distance between the longitudinalbar and the axis B, and a second shaft and means for rotating it inconformity with the variations in the distance between the transversebar and the vertical axis B, a friction disk, means for uniformlyrotating the friction disk, a friction wheel carried by the transversebar and arranged to move along a diameter of the face of the frictiondisk, for the purposes set forth.

10. Apparatus for use in fire control having a fixed base, a sight barmounted on the base capable of rotation about a vertical axis B fixedrelatively to the base, a part mounted upon the base about a verticalaxis C and so supported that the distance CB may be adjusted torepresent on a chosen scale the speed and direction of motion of theobserving ship, a part mounted upon the base about a vertical axis Dadjustable relatively to C, so that CD may be set to represent on thechosen scale the speed and direction of motion of the target, alongitudinal bar maintained parallel to the lineof sight, a transversebar maintained at right angles to the line of sight, the longitudinaland transverse bars being so mounted, as, atall times, to intersect theaxis D and each capable of moving in a direction perpendicular to itslength toward or away from the vertical axis B and turning with thesight bar, a shaft and means for rotating it in conformity with thevariations in the distance between the longitudinal bar and-the axis B,the commutator of a transmitter mounted on or driven by the said shaft,and a second shaft andmeans for rotating it in conformity with thevariations 1n the distance between the transverse bar and the verticalaxis B, the commutator of a transmitter mounted on or driven by the saidshaft, a friction disk, means for uniformly rotating the friction disk,a friction wheel carried by the transverse bar and arranged to moveacross a diameter of the face of the friction disk, for the purposes setforth.

11. Apparatus for use in fire control having a fixed base, a sight barmounted on the base capable of rotation about a vertical axis B fixedrelatively to the base, a part mounted upon the base about a verticalaxis C and so supported that the distance CB may be adjusted torepresent on a chosen scale the speed and direction of motion of theobserving ship, a part mounted upon the base about a vertical axis Dadjustable relatively to C, so that (JD may beset to represent on thechosen scale the speed and direction of motion of the target, alongitudinal bar maintained parallel to the line of sight, a transversebar maintained at right angles to the line of sight, the longitudinaland transverse bars being so mounted as, at all times, to intersect inthe axis D and each capable of moving freely in a directionperpendicular to its length toward or away from the vertical axis B andturning with the sight bar, the longitudinal andv transverse bars eachbeing arranged to bear perpendicularly to its length againstthe part ofwhich D is the axis, for the purposes set forth.

In testimony whereof we affix oursignatures in presence of twowitnesses.

ARCHIBALD BARR. WILLIAM STROUD.

Witnesses:

O. U. PORTER, HAROLD D. JACKSON.

